Determine by using the best sputum cytology methods the prevalence and significance of malignant and atypical cells on screening of a selected high-risk population (heavy smokers 45-69 years of age). Develop the use of the fiberoptic bronchoscope which will extend to segmental bronchi and subsegmental orifices the range within which direct vision and biopsy of endobronchial lesions will be possible. Use these and other related techniques to evolve an optimal program for the localization of occult pulmonary cancers. Determine whether early diagnosis and localization followed by prompt surgical resection have a favorable influence upon long-term survival.